Jeffrey's television career spans 25 years of not only guest starring on various series and shows but he's also credited with creating some
very memorable characters. He is the only actor to have roles on three consecutive series from the Star Trek franchise as well as appearing as different
characters within a single series. For ST: Deep Space Nine he began playing Tiron, a rich patron of Quarks bar followed by Liquidator Brunt, a Ferengi
Commerce Authority agent to which he reprised many times. His most notable recurring role was Weyoun the Vorta, a fan favorite. He has
portrayed this character in over 2 dozen episodes of DS9. Afterwards he moved on to play Penk on ST: Voyager and finally as
another fan favorite the Andorian Shran on Enterprise which featured numerous episodes focused on this character.

Other roles have featured Jeffrey in a wide range of characters from scientists to villains and unseedy individuals not to mention a variety of voice-over roles in animated series.

His more recent noteworthy role was on the USA Network series The 4400 where he created the character Kevin
Burkhoff, a key scientist in the survival of the human race in which he starred in 15 episodes. He was sure to have continued the character for
quite a while more if the series hadn't suffered cancellation after the fourth season.